System and method for higher amortization with plb and vlb defragmentation

ABSTRACT

A method, computer program product, and computer system for identifying, by a computing device, a plurality of blocks. A maximum number of blocks of the plurality of blocks capable of being copied to a new block may be identified. Data from the maximum number of blocks of the plurality of blocks may be copied to the new block.

BACKGROUND

Modern log structured storage systems generally require garbagecollection to create large empty chunks to store, e.g., user data. Thismay involve user data relocation and creates overhead both for user datamovement and virtual layer updates during the defragmentation process.

BRIEF SUMMARY OF DISCLOSURE

In one example implementation, a method, performed by one or morecomputing devices, may include but is not limited to identifying, by acomputing device, a plurality of blocks. A maximum number of blocks ofthe plurality of blocks capable of being copied to a new block may beidentified. Data from the maximum number of blocks of the plurality ofblocks may be copied to the new block.

One or more of the following example features may be included. Theplurality of blocks may include physical layer blocks (PLBs).Identifying the maximum number of blocks of the plurality of blockscapable of being copied to the new block may include identifying anamount of space currently utilized individually by at least a portion ofthe plurality of blocks. Copying the data from the maximum number ofblocks of the plurality of blocks to the new block may include copyingthe data from the plurality of blocks with a least amount of spacecurrently utilized. A sum of the amount of space currently utilizedindividually by the maximum number of blocks may be equal to a size ofthe new block. The plurality of blocks may be organized according to theamount of space currently utilized individually. The plurality of blocksmay be organized into a plurality of buckets according to the amount ofspace currently utilized individually.

In another example implementation, a computing system may include one ormore processors and one or more memories configured to performoperations that may include but are not limited to identifying aplurality of blocks. A maximum number of blocks of the plurality ofblocks capable of being copied to a new block may be identified. Datafrom the maximum number of blocks of the plurality of blocks may becopied to the new block.

One or more of the following example features may be included. Theplurality of blocks may include physical layer blocks (PLBs).Identifying the maximum number of blocks of the plurality of blockscapable of being copied to the new block may include identifying anamount of space currently utilized individually by at least a portion ofthe plurality of blocks. Copying the data from the maximum number ofblocks of the plurality of blocks to the new block may include copyingthe data from the plurality of blocks with a least amount of spacecurrently utilized. A sum of the amount of space currently utilizedindividually by the maximum number of blocks may be equal to a size ofthe new block. The plurality of blocks may be organized according to theamount of space currently utilized individually. The plurality of blocksmay be organized into a plurality of buckets according to the amount ofspace currently utilized individually.

In another example implementation, a computer program product may resideon a computer readable storage medium having a plurality of instructionsstored thereon which, when executed across one or more processors, maycause at least a portion of the one or more processors to performoperations that may include but are not limited to identifying aplurality of blocks. A maximum number of blocks of the plurality ofblocks capable of being copied to a new block may be identified. Datafrom the maximum number of blocks of the plurality of blocks may becopied to the new block.

One or more of the following example features may be included. Theplurality of blocks may include physical layer blocks (PLBs).Identifying the maximum number of blocks of the plurality of blockscapable of being copied to the new block may include identifying anamount of space currently utilized individually by at least a portion ofthe plurality of blocks. Copying the data from the maximum number ofblocks of the plurality of blocks to the new block may include copyingthe data from the plurality of blocks with a least amount of spacecurrently utilized. A sum of the amount of space currently utilizedindividually by the maximum number of blocks may be equal to a size ofthe new block. The plurality of blocks may be organized according to theamount of space currently utilized individually. The plurality of blocksmay be organized into a plurality of buckets according to the amount ofspace currently utilized individually.

The details of one or more example implementations are set forth in theaccompanying drawings and the description below. Other possible examplefeatures and/or possible example advantages will become apparent fromthe description, the drawings, and the claims. Some implementations maynot have those possible example features and/or possible exampleadvantages, and such possible example features and/or possible exampleadvantages may not necessarily be required of some implementations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example diagrammatic view of a defragmentation processcoupled to an example distributed computing network according to one ormore example implementations of the disclosure;

FIG. 2 is an example diagrammatic view of a storage system of FIG. 1according to one or more example implementations of the disclosure;

FIG. 3 is an example diagrammatic view of a storage target of FIG. 1according to one or more example implementations of the disclosure;

FIG. 4 is an example flowchart of a defragmentation process according toone or more example implementations of the disclosure;

FIG. 5 is an example diagrammatic view of a modern PLB defragmentationgarbage collection process according to one or more exampleimplementations of the disclosure;

FIG. 6 is an example diagrammatic view of a redirection processaccording to one or more example implementations of the disclosure;

FIG. 7 is an example diagrammatic view of a redirection processaccording to one or more example implementations of the disclosure; and

FIG. 8 is an example diagrammatic view of a plurality of physical layerblocks according to one or more example implementations of thedisclosure.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION System Overview:

In some implementations, the present disclosure may be embodied as amethod, system, or computer program product. Accordingly, in someimplementations, the present disclosure may take the form of an entirelyhardware implementation, an entirely software implementation (includingfirmware, resident software, micro-code, etc.) or an implementationcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore, insome implementations, the present disclosure may take the form of acomputer program product on a computer-usable storage medium havingcomputer-usable program code embodied in the medium.

In some implementations, any suitable computer usable or computerreadable medium (or media) may be utilized. The computer readable mediummay be a computer readable signal medium or a computer readable storagemedium. The computer-usable, or computer-readable, storage medium(including a storage device associated with a computing device or clientelectronic device) may be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or any suitable combination ofthe foregoing. More specific examples (a non-exhaustive list) of thecomputer-readable medium may include the following: an electricalconnection having one or more wires, a portable computer diskette, ahard disk, a random access memory (RAM), a read-only memory (ROM), anerasable programmable read-only memory (EPROM or Flash memory), anoptical fiber, a portable compact disc read-only memory (CD-ROM), anoptical storage device, a digital versatile disk (DVD), a static randomaccess memory (SRAM), a memory stick, a floppy disk, a mechanicallyencoded device such as punch-cards or raised structures in a groovehaving instructions recorded thereon, a media such as those supportingthe internet or an intranet, or a magnetic storage device. Note that thecomputer-usable or computer-readable medium could even be a suitablemedium upon which the program is stored, scanned, compiled, interpreted,or otherwise processed in a suitable manner, if necessary, and thenstored in a computer memory. In the context of the present disclosure, acomputer-usable or computer-readable, storage medium may be any tangiblemedium that can contain or store a program for use by or in connectionwith the instruction execution system, apparatus, or device.

In some implementations, a computer readable signal medium may include apropagated data signal with computer readable program code embodiedtherein, for example, in baseband or as part of a carrier wave. In someimplementations, such a propagated signal may take any of a variety offorms, including, but not limited to, electro-magnetic, optical, or anysuitable combination thereof. In some implementations, the computerreadable program code may be transmitted using any appropriate medium,including but not limited to the internet, wireline, optical fibercable, RF, etc. In some implementations, a computer readable signalmedium may be any computer readable medium that is not a computerreadable storage medium and that can communicate, propagate, ortransport a program for use by or in connection with an instructionexecution system, apparatus, or device.

In some implementations, computer program code for carrying outoperations of the present disclosure may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java®, Smalltalk, C++ or the like.Java® and all Java-based trademarks and logos are trademarks orregistered trademarks of Oracle and/or its affiliates. However, thecomputer program code for carrying out operations of the presentdisclosure may also be written in conventional procedural programminglanguages, such as the “C” programming language, PASCAL, or similarprogramming languages, as well as in scripting languages such asJavascript, PERL, or Python. The program code may execute entirely onthe user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough a local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theinternet using an Internet Service Provider). In some implementations,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGAs) or other hardwareaccelerators, micro-controller units (MCUs), or programmable logicarrays (PLAs) may execute the computer readable programinstructions/code by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present disclosure.

In some implementations, the flowchart and block diagrams in the figuresillustrate the architecture, functionality, and operation of possibleimplementations of apparatus (systems), methods and computer programproducts according to various implementations of the present disclosure.Each block in the flowchart and/or block diagrams, and combinations ofblocks in the flowchart and/or block diagrams, may represent a module,segment, or portion of code, which comprises one or more executablecomputer program instructions for implementing the specified logicalfunction(s)/act(s). These computer program instructions may be providedto a processor of a general purpose computer, special purpose computer,or other programmable data processing apparatus to produce a machine,such that the computer program instructions, which may execute via theprocessor of the computer or other programmable data processingapparatus, create the ability to implement one or more of thefunctions/acts specified in the flowchart and/or block diagram block orblocks or combinations thereof. It should be noted that, in someimplementations, the functions noted in the block(s) may occur out ofthe order noted in the figures (or combined or omitted). For example,two blocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

In some implementations, these computer program instructions may also bestored in a computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks or combinations thereof.

In some implementations, the computer program instructions may also beloaded onto a computer or other programmable data processing apparatusto cause a series of operational steps to be performed (not necessarilyin a particular order) on the computer or other programmable apparatusto produce a computer implemented process such that the instructionswhich execute on the computer or other programmable apparatus providesteps for implementing the functions/acts (not necessarily in aparticular order) specified in the flowchart and/or block diagram blockor blocks or combinations thereof.

Referring now to the example implementation of FIG. 1, there is showndefragmentation process 10 that may reside on and may be executed by acomputer (e.g., computer 12), which may be connected to a network (e.g.,network 14) (e.g., the internet or a local area network). Examples ofcomputer 12 (and/or one or more of the client electronic devices notedbelow) may include, but are not limited to, a storage system (e.g., aNetwork Attached Storage (NAS) system, a Storage Area Network (SAN)), apersonal computer(s), a laptop computer(s), mobile computing device(s),a server computer, a series of server computers, a mainframecomputer(s), or a computing cloud(s). As is known in the art, a SAN mayinclude one or more of the client electronic devices, including a RAIDdevice and a NAS system. In some implementations, each of theaforementioned may be generally described as a computing device. Incertain implementations, a computing device may be a physical or virtualdevice. In many implementations, a computing device may be any devicecapable of performing operations, such as a dedicated processor, aportion of a processor, a virtual processor, a portion of a virtualprocessor, portion of a virtual device, or a virtual device. In someimplementations, a processor may be a physical processor or a virtualprocessor. In some implementations, a virtual processor may correspondto one or more parts of one or more physical processors. In someimplementations, the instructions/logic may be distributed and executedacross one or more processors, virtual or physical, to execute theinstructions/logic. Computer 12 may execute an operating system, forexample, but not limited to, Microsoft® Windows®; Mac® OS X®; Red Hat®Linux®, Windows® Mobile, Chrome OS, Blackberry OS, Fire OS, or a customoperating system. (Microsoft and Windows are registered trademarks ofMicrosoft Corporation in the United States, other countries or both; Macand OS X are registered trademarks of Apple Inc. in the United States,other countries or both; Red Hat is a registered trademark of Red HatCorporation in the United States, other countries or both; and Linux isa registered trademark of Linus Torvalds in the United States, othercountries or both).

In some implementations, as will be discussed below in greater detail, adefragmentation process, such as defragmentation process 10 of FIG. 1,may identifying a plurality of blocks. A maximum number of blocks of theplurality of blocks capable of being copied to a new block may beidentified. Data from the maximum number of blocks of the plurality ofblocks may be copied to the new block.

In some implementations, the instruction sets and subroutines ofdefragmentation process 10, which may be stored on storage device, suchas storage device 16, coupled to computer 12, may be executed by one ormore processors and one or more memory architectures included withincomputer 12. In some implementations, storage device 16 may include butis not limited to: a hard disk drive; all forms of flash memory storagedevices; a tape drive; an optical drive; a RAID array (or other array);a random access memory (RAM); a read-only memory (ROM); or combinationthereof. In some implementations, storage device 16 may be organized asan extent, an extent pool, a RAID extent (e.g., an example 4D+1P R5,where the RAID extent may include, e.g., five storage device extentsthat may be allocated from, e.g., five different storage devices), amapped RAID (e.g., a collection of RAID extents), or combinationthereof.

In some implementations, network 14 may be connected to one or moresecondary networks (e.g., network 18), examples of which may include butare not limited to: a local area network; a wide area network or othertelecommunications network facility; or an intranet, for example. Thephrase “telecommunications network facility,” as used herein, may referto a facility configured to transmit, and/or receive transmissionsto/from one or more mobile client electronic devices (e.g., cellphones,etc.) as well as many others.

In some implementations, computer 12 may include a data store, such as adatabase (e.g., relational database, object-oriented database,triplestore database, etc.) and may be located within any suitablememory location, such as storage device 16 coupled to computer 12. Insome implementations, data, metadata, information, etc. describedthroughout the present disclosure may be stored in the data store. Insome implementations, computer 12 may utilize any known databasemanagement system such as, but not limited to, DB2, in order to providemulti-user access to one or more databases, such as the above notedrelational database. In some implementations, the data store may also bea custom database, such as, for example, a flat file database or an XMLdatabase. In some implementations, any other form(s) of a data storagestructure and/or organization may also be used. In some implementations,defragmentation process 10 may be a component of the data store, astandalone application that interfaces with the above noted data storeand/or an applet/application that is accessed via client applications22, 24, 26, 28. In some implementations, the above noted data store maybe, in whole or in part, distributed in a cloud computing topology. Inthis way, computer 12 and storage device 16 may refer to multipledevices, which may also be distributed throughout the network.

In some implementations, computer 12 may execute a storage managementapplication (e.g., storage management application 21), examples of whichmay include, but are not limited to, e.g., a storage system application,a cloud computing application, a data synchronization application, adata migration application, a garbage collection application, or otherapplication that allows for the implementation and/or management of datain a clustered (or non-clustered) environment (or the like). In someimplementations, defragmentation process 10 and/or storage managementapplication 21 may be accessed via one or more of client applications22, 24, 26, 28. In some implementations, defragmentation process 10 maybe a standalone application, or may be anapplet/application/script/extension that may interact with and/or beexecuted within storage management application 21, a component ofstorage management application 21, and/or one or more of clientapplications 22, 24, 26, 28. In some implementations, storage managementapplication 21 may be a standalone application, or may be anapplet/application/script/extension that may interact with and/or beexecuted within defragmentation process 10, a component ofdefragmentation process 10, and/or one or more of client applications22, 24, 26, 28. In some implementations, one or more of clientapplications 22, 24, 26, 28 may be a standalone application, or may bean applet/application/script/extension that may interact with and/or beexecuted within and/or be a component of defragmentation process 10and/or storage management application 21. Examples of clientapplications 22, 24, 26, 28 may include, but are not limited to, e.g., astorage system application, a cloud computing application, a datasynchronization application, a data migration application, a garbagecollection application, or other application that allows for theimplementation and/or management of data in a clustered (ornon-clustered) environment (or the like), a standard and/or mobile webbrowser, an email application (e.g., an email client application), atextual and/or a graphical user interface, a customized web browser, aplugin, an Application Programming Interface (API), or a customapplication. The instruction sets and subroutines of client applications22, 24, 26, 28, which may be stored on storage devices 30, 32, 34, 36,coupled to client electronic devices 38, 40, 42, 44, may be executed byone or more processors and one or more memory architectures incorporatedinto client electronic devices 38, 40, 42, 44.

In some implementations, one or more of storage devices 30, 32, 34, 36,may include but are not limited to: hard disk drives; flash drives, tapedrives; optical drives; RAID arrays; random access memories (RAM); andread-only memories (ROM). Examples of client electronic devices 38, 40,42, 44 (and/or computer 12) may include, but are not limited to, apersonal computer (e.g., client electronic device 38), a laptop computer(e.g., client electronic device 40), a smart/data-enabled, cellularphone (e.g., client electronic device 42), a notebook computer (e.g.,client electronic device 44), a tablet, a server, a television, a smarttelevision, a smart speaker, an Internet of Things (IoT) device, a media(e.g., video, photo, etc.) capturing device, and a dedicated networkdevice. Client electronic devices 38, 40, 42, 44 may each execute anoperating system, examples of which may include but are not limited to,Android, Apple® iOS®, Mac® OS X®; Red Hat® Linux®, Windows® Mobile,Chrome OS, Blackberry OS, Fire OS, or a custom operating system.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality ofdefragmentation process 10 (and vice versa). Accordingly, in someimplementations, defragmentation process 10 may be a purely server-sideapplication, a purely client-side application, or a hybridserver-side/client-side application that is cooperatively executed byone or more of client applications 22, 24, 26, 28 and/or defragmentationprocess 10.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality ofstorage management application 21 (and vice versa). Accordingly, in someimplementations, storage management application 21 may be a purelyserver-side application, a purely client-side application, or a hybridserver-side/client-side application that is cooperatively executed byone or more of client applications 22, 24, 26, 28 and/or storagemanagement application 21. As one or more of client applications 22, 24,26, 28, defragmentation process 10, and storage management application21, taken singly or in any combination, may effectuate some or all ofthe same functionality, any description of effectuating suchfunctionality via one or more of client applications 22, 24, 26, 28,defragmentation process 10, storage management application 21, orcombination thereof, and any described interaction(s) between one ormore of client applications 22, 24, 26, 28, defragmentation process 10,storage management application 21, or combination thereof to effectuatesuch functionality, should be taken as an example only and not to limitthe scope of the disclosure.

In some implementations, one or more of users 46, 48, 50, 52 may accesscomputer 12 and defragmentation process 10 (e.g., using one or more ofclient electronic devices 38, 40, 42, 44) directly through network 14 orthrough secondary network 18. Further, computer 12 may be connected tonetwork 14 through secondary network 18, as illustrated with phantomlink line 54. Defragmentation process 10 may include one or more userinterfaces, such as browsers and textual or graphical user interfaces,through which users 46, 48, 50, 52 may access defragmentation process10.

In some implementations, the various client electronic devices may bedirectly or indirectly coupled to network 14 (or network 18). Forexample, client electronic device 38 is shown directly coupled tonetwork 14 via a hardwired network connection. Further, clientelectronic device 44 is shown directly coupled to network 18 via ahardwired network connection. Client electronic device 40 is shownwirelessly coupled to network 14 via wireless communication channel 56established between client electronic device 40 and wireless accesspoint (i.e., WAP) 58, which is shown directly coupled to network 14. WAP58 may be, for example, an IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, Wi-Fi®, RFID, and/or Bluetooth™ (including Bluetooth™ LowEnergy) device that is capable of establishing wireless communicationchannel 56 between client electronic device 40 and WAP 58. Clientelectronic device 42 is shown wirelessly coupled to network 14 viawireless communication channel 60 established between client electronicdevice 42 and cellular network/bridge 62, which is shown by exampledirectly coupled to network 14.

In some implementations, some or all of the IEEE 802.11x specificationsmay use Ethernet protocol and carrier sense multiple access withcollision avoidance (i.e., CSMA/CA) for path sharing. The various802.11x specifications may use phase-shift keying (i.e., PSK) modulationor complementary code keying (i.e., CCK) modulation, for example.Bluetooth™ (including Bluetooth™ Low Energy) is a telecommunicationsindustry specification that allows, e.g., mobile phones, computers,smart phones, and other electronic devices to be interconnected using ashort-range wireless connection. Other forms of interconnection (e.g.,Near Field Communication (NFC)) may also be used.

In some implementations, various I/O requests (e.g., I/O request 15) maybe sent from, e.g., client applications 22, 24, 26, 28 to, e.g.,computer 12. Examples of I/O request 15 may include but are not limitedto, data write requests (e.g., a request that content be written tocomputer 12) and data read requests (e.g., a request that content beread from computer 12).

Data Storage System:

Referring also to the example implementation of FIGS. 2-3 (e.g., wherecomputer 12 may be configured as a data storage system), computer 12 mayinclude storage processor 100 and a plurality of storage targets (e.g.,storage targets 102, 104, 106, 108, 110). In some implementations,storage targets 102, 104, 106, 108, 110 may include any of theabove-noted storage devices. In some implementations, storage targets102, 104, 106, 108, 110 may be configured to provide various levels ofperformance and/or high availability. For example, storage targets 102,104, 106, 108, 110 may be configured to form a non-fully-duplicativefault-tolerant data storage system (such as a non-fully-duplicative RAIDdata storage system), examples of which may include but are not limitedto: RAID 3 arrays, RAID 4 arrays, RAID 5 arrays, and/or RAID 6 arrays.It will be appreciated that various other types of RAID arrays may beused without departing from the scope of the present disclosure.

While in this particular example, computer 12 is shown to include fivestorage targets (e.g., storage targets 102, 104, 106, 108, 110), this isfor example purposes only and is not intended limit the presentdisclosure. For instance, the actual number of storage targets may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

Further, the storage targets (e.g., storage targets 102, 104, 106, 108,110) included with computer 12 may be configured to form a plurality ofdiscrete storage arrays. For instance, and assuming for example purposesonly that computer 12 includes, e.g., ten discrete storage targets, afirst five targets (of the ten storage targets) may be configured toform a first RAID array and a second five targets (of the ten storagetargets) may be configured to form a second RAID array.

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may be configured to store coded data (e.g., via storagemanagement process 21), wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage targets102, 104, 106, 108, 110. Examples of such coded data may include but isnot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage targets 102, 104, 106, 108, 110 or maybe stored within a specific storage target.

Examples of storage targets 102, 104, 106, 108, 110 may include one ormore data arrays, wherein a combination of storage targets 102, 104,106, 108, 110 (and any processing/control systems associated withstorage management application 21) may form data array 112.

The manner in which computer 12 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, computer 12 may be configured as a SAN (i.e., a Storage AreaNetwork), in which storage processor 100 may be, e.g., a dedicatedcomputing system and each of storage targets 102, 104, 106, 108, 110 maybe a RAID device. An example of storage processor 100 may include but isnot limited to a VPLEX™ system offered by Dell EMC™ of Hopkinton, Mass.

In the example where computer 12 is configured as a SAN, the variouscomponents of computer 12 (e.g., storage processor 100, and storagetargets 102, 104, 106, 108, 110) may be coupled using networkinfrastructure 114, examples of which may include but are not limited toan Ethernet (e.g., Layer 2 or Layer 3) network, a fiber channel network,an InfiniBand network, or any other circuit switched/packet switchednetwork.

As discussed above, various I/O requests (e.g., I/O request 15) may begenerated. For example, these I/O requests may be sent from, e.g.,client applications 22, 24, 26, 28 to, e.g., computer 12.Additionally/alternatively (e.g., when storage processor 100 isconfigured as an application server or otherwise), these I/O requestsmay be internally generated within storage processor 100 (e.g., viastorage management process 21). Examples of I/O request 15 may includebut are not limited to data write request 116 (e.g., a request thatcontent 118 be written to computer 12) and data read request 120 (e.g.,a request that content 118 be read from computer 12).

In some implementations, during operation of storage processor 100,content 118 to be written to computer 12 may be received and/orprocessed by storage processor 100 (e.g., via storage management process21). Additionally/alternatively (e.g., when storage processor 100 isconfigured as an application server or otherwise), content 118 to bewritten to computer 12 may be internally generated by storage processor100 (e.g., via storage management process 21).

As discussed above, the instruction sets and subroutines of storagemanagement application 21, which may be stored on storage device 16included within computer 12, may be executed by one or more processorsand one or more memory architectures included with computer 12.Accordingly, in addition to being executed on storage processor 100,some or all of the instruction sets and subroutines of storagemanagement application 21 (and/or defragmentation process 10) may beexecuted by one or more processors and one or more memory architecturesincluded with data array 112.

In some implementations, storage processor 100 may include front endcache memory system 122. Examples of front end cache memory system 122may include but are not limited to a volatile, solid-state, cache memorysystem (e.g., a dynamic RAM cache memory system), a non-volatile,solid-state, cache memory system (e.g., a flash-based, cache memorysystem), and/or any of the above-noted storage devices.

In some implementations, storage processor 100 may initially storecontent 118 within front end cache memory system 122. Depending upon themanner in which front end cache memory system 122 is configured, storageprocessor 100 (e.g., via storage management process 21) may immediatelywrite content 118 to data array 112 (e.g., if front end cache memorysystem 122 is configured as a write-through cache) or may subsequentlywrite content 118 to data array 112 (e.g., if front end cache memorysystem 122 is configured as a write-back cache).

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may include a backend cache memory system. Examples of thebackend cache memory system may include but are not limited to avolatile, solid-state, cache memory system (e.g., a dynamic RAM cachememory system), a non-volatile, solid-state, cache memory system (e.g.,a flash-based, cache memory system), and/or any of the above-notedstorage devices.

Storage Targets:

As discussed above, one or more of storage targets 102, 104, 106, 108,110 may be a RAID device. For instance, and referring also to FIG. 3,there is shown example target 150, wherein target 150 may be one exampleimplementation of a RAID implementation of, e.g., storage target 102,storage target 104, storage target 106, storage target 108, and/orstorage target 110. An example of target 150 may include but is notlimited to a VNX™ system offered by Dell EMC™ of Hopkinton, Mass.Examples of storage devices 154, 156, 158, 160, 162 may include one ormore electro-mechanical hard disk drives, one or more solid-state/flashdevices, and/or any of the above-noted storage devices. It will beappreciated that while the term “disk” or “drive” may be usedthroughout, these may refer to and be used interchangeably with anytypes of appropriate storage devices as the context and functionality ofthe storage device permits.

In some implementations, target 150 may include storage processor 152and a plurality of storage devices (e.g., storage devices 154, 156, 158,160, 162). Storage devices 154, 156, 158, 160, 162 may be configured toprovide various levels of performance and/or high availability (e.g.,via storage management process 21). For example, one or more of storagedevices 154, 156, 158, 160, 162 (or any of the above-noted storagedevices) may be configured as a RAID 0 array, in which data is stripedacross storage devices. By striping data across a plurality of storagedevices, improved performance may be realized. However, RAID 0 arraysmay not provide a level of high availability. Accordingly, one or moreof storage devices 154, 156, 158, 160, 162 (or any of the above-notedstorage devices) may be configured as a RAID 1 array, in which data ismirrored between storage devices. By mirroring data between storagedevices, a level of high availability may be achieved as multiple copiesof the data may be stored within storage devices 154, 156, 158, 160,162.

While storage devices 154, 156, 158, 160, 162 are discussed above asbeing configured in a RAID 0 or RAID 1 array, this is for examplepurposes only and not intended to limit the present disclosure, as otherconfigurations are possible. For example, storage devices 154, 156, 158,160, 162 may be configured as a RAID 3, RAID 4, RAID 5 or RAID 6 array.

While in this particular example, target 150 is shown to include fivestorage devices (e.g., storage devices 154, 156, 158, 160, 162), this isfor example purposes only and not intended to limit the presentdisclosure. For instance, the actual number of storage devices may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

In some implementations, one or more of storage devices 154, 156, 158,160, 162 may be configured to store (e.g., via storage managementprocess 21) coded data, wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage devices154, 156, 158, 160, 162. Examples of such coded data may include but arenot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage devices 154, 156, 158, 160, 162 or maybe stored within a specific storage device.

The manner in which target 150 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, target 150 may be a RAID device in which storage processor 152is a RAID controller card and storage devices 154, 156, 158, 160, 162are individual “hot-swappable” hard disk drives. Another example oftarget 150 may be a RAID system, examples of which may include but arenot limited to an NAS (i.e., Network Attached Storage) device or a SAN(i.e., Storage Area Network).

In some implementations, storage target 150 may execute all or a portionof storage management application 21. The instruction sets andsubroutines of storage management application 21, which may be stored ona storage device (e.g., storage device 164) coupled to storage processor152, may be executed by one or more processors and one or more memoryarchitectures included with storage processor 152. Storage device 164may include but is not limited to any of the above-noted storagedevices.

As discussed above, computer 12 may be configured as a SAN, whereinstorage processor 100 may be a dedicated computing system and each ofstorage targets 102, 104, 106, 108, 110 may be a RAID device.Accordingly, when storage processor 100 processes data requests 116,120, storage processor 100 (e.g., via storage management process 21) mayprovide the appropriate requests/content (e.g., write request 166,content 168 and read request 170) to, e.g., storage target 150 (which isrepresentative of storage targets 102, 104, 106, 108 and/or 110).

In some implementations, during operation of storage processor 152,content 168 to be written to target 150 may be processed by storageprocessor 152 (e.g., via storage management process 21). Storageprocessor 152 may include cache memory system 172. Examples of cachememory system 172 may include but are not limited to a volatile,solid-state, cache memory system (e.g., a dynamic RAM cache memorysystem) and/or a non-volatile, solid-state, cache memory system (e.g., aflash-based, cache memory system). During operation of storage processor152, content 168 to be written to target 150 may be received by storageprocessor 152 (e.g., via storage management process 21) and initiallystored (e.g., via storage management process 21) within front end cachememory system 172.

The Defragmentation Process:

As discussed above and referring also at least to the exampleimplementations of FIGS. 4-7, defragmentation process 10 may identify400, by a computing device, a plurality of blocks. Defragmentationprocess 10 may identify 402 a maximum number of blocks of the pluralityof blocks capable of being copied to a new block. Defragmentationprocess 10 may copy 404 data from the maximum number of blocks of theplurality of blocks to the new block.

As noted above, modern log structured storage systems generally requiregarbage collection to create large empty chunks to store, e.g., userdata. This may involve user data relocation and creates overhead bothfor user data movement and virtual layer updates during thedefragmentation process. As will be discussed below, defragmentationprocess 10 may reach higher amortization during PLB defragmentation.

For example, in some implementations, defragmentation process 10 mayidentify 400 a plurality of blocks (e.g., physical layer blocks (PLBs)).For instance, and referring at least to the example FIG. 5, an examplediagrammatic view of a modern PLB defragmentation (garbage collection)process 500 is shown. The modern log structured storage systems usuallyuse 3-level indirection scheme to access user data:

Leaf: Logical Block Address (LBA) representation layer, generallyorganized as a tree. Each leaf entry generally corresponds to a specificLBA range.

Virtual Layer Block (VLB): Isolates LBA layer from physical storage.Encapsulates physical location of the user data and allows datarelocation without necessity to update Leafs.

PLB: In log structured systems, the data is stored in contiguous chunksof data, called PLB (e.g., 2 MB chunks). The actual user data pagesreside inside, and they may be referenced by one or more VLBs.

As such, the structure may be generally described as: Leaf (LBArepresentation)→Virtual Block (VLB)→Physical Block (PLB).

For example, after a write operation: Leaf, corresponding to LBA willpoint to VLB that contains references to PLBs where the user data isstored. When the write is deduped, a second leaf will point to the sameVLB as a first leaf. Since there might be multiple leaves pointing tothe same virtual block, VLBs may manage reference count for every entry.To achieve efficiency, a write to empty PLB is preferred. Therefore, aPLB's defragmentation process is applied to merge PLBs with free spaceand create empty PLBs for future use. In the simplest case for examplepurposes only and ease of explanation, PLB defragmentation takes 2 PLBsand merges their data to a single PLB as follows and shown in FIG. 5:

Initial state: VLB1→PLB1, VLB2→PLB2

PLB defragmentation process:

Take data from PLB1, PLB2

Write into PLB3

Releasing PLB2, PLB1.

After, PLB defragmentation state is: VLB1→PLB3, VLB2→PLB3

Note that PLB defragmentation reduced only the number of used PhysicalBlocks. The number of Virtual Blocks remains the same. All VLBs areupdated to point to the newly created PLB. Thus, the example problem ofcurrent VLB fragmentation arises. The more PLB defragmentations run, themore virtual blocks are aggregated and less populated they become. Thisincreases VLBs usages, reduces updates amortization and might breakvarious system level limitations like maximum Virtual Blocks perPhysical Block.

Some techniques may try to address this by VLB defragmentation usingredirection. For example, and referring at least to the example FIG. 6,an example diagrammatic view of a redirection process 600 is shown. Themain idea of this solution is assigning each VLB a generation index.Leaves will point to an entry into specific generation. The redirectionitself is applied by moving the data reference to a new VLB, increasingthe old VLB generation index and storing the link to the new VLB in anold VLB in a redirection table for the previous generation. When thishappens, the link from the Leaf will hit the VLB with a different index,will read the redirection table and go to the redirected VLB. Thismethod allows relocation of user data to a new PLB without updating theLeaf (only the VLB update is required).

Amortization Calculations:

Referring to the example FIG. 7, a simple approach of redirection 700 isshown. Assume C is the average uniform compression factor, and N is thenumber of PLBs taken for defragmentation. In the simple approach, 2 PLBswith C VLBs each are being redirected into the new single PLB with CVLBs. This is possible assuming we select the PLBs with total utilizedcapacity equals to 1 PLB, assuming C is a uniform compression factor.

-   -   Writes 1 PLB    -   Writes 1*C VLB    -   Redirects 2*C VLBs    -   Total released 1 PLB and 1*C VLBs (2* C redirected VLBs−1*C VLB)    -   Release 2 VLBs, consume 1 VLB        Release 1 VLB    -   Total redirected entries equivalent to a single VLB (otherwise        garbage collection may not be performed)    -   Everything is multiplied by factor C)    -   Total redirected entries: 1*C VLBs (512*C VLB entries)

As is clear, this solution is not optimal. Consider the common casewhere defragmentation is run over N PLBs that are referenced by N*CVLBs. For each cycle enough PLBs are accumulated to write a fullypopulated PLB:

-   -   Write 1 PLB    -   Write 1*C VLBs    -   Redirect N*C VLBs (notably, it is not necessarily important how        many redirected VLBs there are, but rather how many entries go        through redirection, and in both approaches it is the same        number: 1*C VLB entries.)    -   Total release N−1 PLBs and (N−1)*C VLBs    -   Total redirected entries: 1*C VLB (512)

The optimized method had the same amount of work to be done:

-   -   Write (1 PLB)+Write (1*C VLBs)

But the effective result is different:

-   -   Basic method: 1 PLB, 1*C VLBs released    -   Defragmentation process 10 method: N−1 PLBs, (N−1)*C VLBs        released

The more PLBs taken into a single defragmentation cycle, the betteramortization is achieved by the factor of N. Therefore, as will bediscussed below, defragmentation process 10 may identify and select themaximum number of the most free PLBs for a single defragmentation cycle.

For example, in some implementations, defragmentation process 10 mayidentify 400 a plurality of blocks (e.g., physical layer blocks (PLBs)).For instance, and referring to the example implementation of FIG. 8, aplurality of PLBs 800 are shown that are eligible for being copied to anew block during defragmentation. Each of these PLBs may be identified400 by defragmentation process 10.

In some implementations, defragmentation process 10 may identify 402 amaximum number of blocks of the plurality of blocks capable of beingcopied to a new block. For instance, assume for example purposes onlythat each PLB is filled at the capacity indicated. Based ondefragmentation overhead calculation, it is not efficient to perform 2PLBS→1 PLB operation. Instead it is much better to create a new PLB fromas many smaller PLBs as possible (i.e., the maximum number of PLBs thatcan be stored in the new PLB). That is, in the general case, PLBdefragmentation should select the set of PLBs and VLBs as large aspossible so that sum of all the entries in the PLBs is equal to the sizeof one single PLB (the new PLB). This strategy results in highestamortization. As such, identifying 402 the maximum number of blocks ofthe plurality of blocks capable of being copied to the new block mayinclude identifying 406 an amount of space currently utilizedindividually by at least a portion of the plurality of blocks, where asum of the amount of space currently utilized individually by themaximum number of blocks may be equal to a size of the new block (e.g.,2 MB). For example, while it may be possible to copy PLB9 (at 75%capacity) and PLB3 (at 25% capacity) in a single cycle into the new PLB(at 100% capacity, or 2 MB, after copying), doing so creates overhead ofresources required to do so (e.g., redirection). Instead, by identifyingthe capacity of each PLB individually, defragmentation process 10 maydetermine that the amount of resources required to copy PLB1 (at 5%capacity), PLB4 (at 4% capacity), PLB5 (at 1% capacity), PLB2 (at 10%capacity), PLB7 (at 30% capacity), and PLB6 (at 50% capacity) into thenew PLB (at 100% capacity, or 2 MB, after copying) would be lower (e.g.,the amortization is higher and the number of redirections in the systemis reduced), as more PLBs are being copied in a single cycle. As such,in some implementations, defragmentation process 10 may copy 404 datafrom the identified maximum number of blocks (i.e., PLB1, PLB4, PLB5,PLB2, PLB7, and PLB6) of the plurality of blocks to the new block (PLBNEW).

In some implementations, copying 404 the data from the maximum number ofblocks of the plurality of blocks to the new block may include copying408 the data from the plurality of blocks with a least amount of spacecurrently utilized. For instance, by copying the blocks with the leastamount of space currently being utilized per block (as opposed tocopying the blocks with higher amounts of space currently utilized, suchas PLB9 and PLB3), there is a greater chance that more blocks will beable to be copied in a single cycle.

In some implementations, the plurality of blocks may be organizedaccording to the amount of space currently utilized individually (e.g.,in increasing or decreasing order). As another example, the plurality ofblocks may be organized into a plurality of buckets according to theamount of space currently utilized individually. For instance, the PLBsmay be arranged according to their utilized capacity in buckets (shownin FIG. 8). For example, suppose there are 10 buckets for capacity, thenPLBs that are 43.4% full will be in bucket of, e.g., 40%-50%, and 74%will go to bucket of, e.g., 70%-80%, etc.

In some implementations, for each PLB, there may be a small PLBDesc (PLBdescriptor) metadata block that holds “back pointers” from PLB to VLB.It may also hold any additional metadata associated with this PLB, andcapacity bucket might be stored there. Notably, the bucket associationinformation is generally not stored persistently. Instead may only bestored in volatile memory and during recovery it is lazy reevaluated.There may be a background thread that reads the PLB, its associated VLBand reconstructs the PLB capacity bucket.

The terminology used herein is for the purpose of describing particularimplementations only and is not intended to be limiting of thedisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. As used herein, the language “at least one of A, B,and C” (and the like) should be interpreted as covering only A, only B,only C, or any combination of the three, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps (notnecessarily in a particular order), operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps (not necessarily in a particular order),operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents (e.g., ofall means or step plus function elements) that may be in the claimsbelow are intended to include any structure, material, or act forperforming the function in combination with other claimed elements asspecifically claimed. The description of the present disclosure has beenpresented for purposes of illustration and description, but is notintended to be exhaustive or limited to the disclosure in the formdisclosed. Many modifications, variations, substitutions, and anycombinations thereof will be apparent to those of ordinary skill in theart without departing from the scope and spirit of the disclosure. Theimplementation(s) were chosen and described in order to explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various implementation(s) with various modifications and/or anycombinations of implementation(s) as are suited to the particular usecontemplated.

Having thus described the disclosure of the present application indetail and by reference to implementation(s) thereof, it will beapparent that modifications, variations, and any combinations ofimplementation(s) (including any modifications, variations,substitutions, and combinations thereof) are possible without departingfrom the scope of the disclosure defined in the appended claims.

What is claimed is:
 1. A computer-implemented method comprising:identifying, by a computing device, a plurality of blocks; identifying amaximum number of blocks of the plurality of blocks capable of beingcopied to a new block; and copying data from the maximum number ofblocks of the plurality of blocks to the new block.
 2. Thecomputer-implemented method of claim 1 wherein the plurality of blocksinclude physical layer blocks (PLBs).
 3. The computer-implemented methodof claim 1 wherein identifying the maximum number of blocks of theplurality of blocks capable of being copied to the new block includesidentifying an amount of space currently utilized individually by atleast a portion of the plurality of blocks.
 4. The computer-implementedmethod of claim 3 wherein copying the data from the maximum number ofblocks of the plurality of blocks to the new block includes copying thedata from the plurality of blocks with a least amount of space currentlyutilized.
 5. The computer-implemented method of claim 3 wherein a sum ofthe amount of space currently utilized individually by the maximumnumber of blocks is equal to a size of the new block.
 6. Thecomputer-implemented method of claim 3 wherein the plurality of blocksare organized according to the amount of space currently utilizedindividually.
 7. The computer-implemented method of claim 6 wherein theplurality of blocks are organized into a plurality of buckets accordingto the amount of space currently utilized individually.
 8. A computerprogram product residing on a computer readable storage medium having aplurality of instructions stored thereon which, when executed across oneor more processors, causes at least a portion of the one or moreprocessors to perform operations comprising: identifying a plurality ofblocks; identifying a maximum number of blocks of the plurality ofblocks capable of being copied to a new block; and copying data from themaximum number of blocks of the plurality of blocks to the new block. 9.The computer program product of claim 8 wherein the plurality of blocksinclude physical layer blocks (PLBs).
 10. The computer program productof claim 8 wherein identifying the maximum number of blocks of theplurality of blocks capable of being copied to the new block includesidentifying an amount of space currently utilized individually by atleast a portion of the plurality of blocks.
 11. The computer programproduct of claim 10 wherein copying the data from the maximum number ofblocks of the plurality of blocks to the new block includes copying thedata from the plurality of blocks with a least amount of space currentlyutilized.
 12. The computer program product of claim 10 wherein a sum ofthe amount of space currently utilized individually by the maximumnumber of blocks is equal to a size of the new block.
 13. The computerprogram product of claim 10 wherein the plurality of blocks areorganized according to the amount of space currently utilizedindividually.
 14. The computer program product of claim 13 wherein theplurality of blocks are organized into a plurality of buckets accordingto the amount of space currently utilized individually.
 15. A computingsystem including one or more processors and one or more memoriesconfigured to perform operations comprising: identifying a plurality ofblocks; identifying a maximum number of blocks of the plurality ofblocks capable of being copied to a new block; and copying data from themaximum number of blocks of the plurality of blocks to the new block.16. The computing system of claim 15 wherein the plurality of blocksinclude physical layer blocks (PLBs).
 17. The computing system of claim15 wherein identifying the maximum number of blocks of the plurality ofblocks capable of being copied to the new block includes identifying anamount of space currently utilized individually by at least a portion ofthe plurality of blocks.
 18. The computing system of claim 17 whereincopying the data from the maximum number of blocks of the plurality ofblocks to the new block includes copying the data from the plurality ofblocks with a least amount of space currently utilized.
 19. Thecomputing system of claim 17 wherein a sum of the amount of spacecurrently utilized individually by the maximum number of blocks is equalto a size of the new block.
 20. The computing system of claim 17 whereinthe plurality of blocks are organized according to the amount of spacecurrently utilized individually.